Define \(\mathcal {R}\) , \(\mathcal {G}\)  and \(\mathcal {B}\)  to be the sets that collect the pixels where the original red, green and blue values are captured respectively. Malvar-He-Cutler propose estimating the missing color values by a weighted combination of the local intra-channel average and the Laplacian of another channel [1]}. For example, at a pixel \([m,n]\in \mathcal {R}\) , the green value \(G[m,n]\)  is estimated by
\(G[m,n]\approx \bar{G} + \alpha \Delta R[m,n],\) 
